Transition-metal-catalyzed oxidation of metallic Sn in NiO/SnO2 nanocomposite.

It is well accepted that metallic tin as a discharge (reduction) product of SnO(x) cannot be electrochemically oxidized below 3.00 V versus Li(+)/Li(0) due to the high stability of Li2O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni2 SnO4 and NiO/SnO2 nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to SnO2 below 3.00 V. As a result, the reversible lithium-storage capacities of the nanocomposite reach 970 mAh g(-1) or above, much higher than the theoretical capacity (ca. 750 mAh g(-1)) of SnO2, NiO, or their composites. These findings extend the well-known electrochemical conversion reaction to non-transition-metal compounds and may have important applications, for example, in constructing high-capacity electrode materials and efficient catalysts.